Toolholder for thread rolling tools



A ril 22, 1969 H. c. BURNETT 3, 8

TOOLHOLDER FOR THREAD ROLLING TOOLS Filed Feb. 8, 1967 Sheet -of :5

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April 22, 1969 H. c. BURNETT 3,439,518

TOOLHOLDER FOR THREAD ROLLING TOOLS Filed Feb. 8, 1967 Sheet L of s.lEl.

INVENTOR.

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flrratyzKi April 22, 1969 H. c. BURNETT 3,439,518

TOOLHOLDER FOR THREAD ROLLING TOOLS Filed Feb. 8. 1967 I Sheet 3 of sINVENTOR.

BY /W% i% afraid/1% United States Patent 3,439,518 TOOLHOLDER FOR THREADROLLING TOOLS Herbert C. Burnett, Fraser, Mich., assignor to Detroit Tapand Tool Co., a corporation of Delaware Filed Feb. 8, 1967, Ser. No.614,658 Int. Cl. B21b 1/10; B21h 3/04; B21d 17/00 U.S. Cl. 72-101 ClaimsABSTRACT OF THE DISCLOSURE This application discloses a thread rollingtoolholder having a two piece, pivoted base with fixed shafts supportedin the outer end of each piece. The shafts have a cantilevered end uponwhich thread rolling tools or the like are supported for rotation andare axially located by thrust bearings. Pivotal adjustment of the twobase pieces permits different size workpieces to be accommodated. Asynchronizing drive gear train is supported within the base and isadapted to be drivingly coupled to each of the tools so as tosynchronize their rotation. The use of tapered bores for the toolholding shafts allows adjustment to compensate for wear in thecomponents. In addition, one of the drive gears is supported formovement out of mesh with the other gears so as to adjust thesynchronization between the tools.

Background of the invention This invention relates to a toolholder forthread rolling tools and more particularly to an improved toolholderwherein the tools are mounted outboard of the holder base.

Various types of thread rolling toolholders have been employed forforming threads or for use in other screw machine operations. One suchprior art type tool holder is shown in United States Letters Patent3,217,523, issued Nov. 16, 1965, entitled, Holder for Thread RollingTools, and in which I am a coinventor with James M. Burnett. This patentshows a holder for thread rolling tools that adapts itself to the use ofdifferent size tools and permits the forming of threads on differentsize articles. The holder shown in this patent provides for inboardmounting of the tools. That is, the tools are supported on shaftsbetween the shaft ends and within the holder base. Although this type ofconstruction has advantages in certain applications, it is notsatisfactory for use in the formation of threads immediately adjacent arelatively large shoulder or on a relatively short workpiece. Thepresent invention solves this problem by providing for the outboardmounting of the rolling tools, as well as other features which will bedescribed.

It is, therefore, an object of this invention to provide an improvedtoolholder which overcomes the aforementioned disadvantages of knownconstructions.

It is another object of this invention to provide an outboard toolholderthat does not require expensive adjustable bearings, yet provides forsimple adjustment of the rotational axes of the rolling tools toaccommodate wear and the like.

It is still a further object of this invention to provide an adjustableoutboard toolholder that will support tools of different sizes andaccommodate workpieces of different dimensions.

Summary of the invention A toolholder embodying this invention isparticularly adapted to support thread rolling tools or the like. Thetoolholder is comprised of a holder base and a pair of spaced toolsupporting shafts held against rotation by the holder base. One end ofeach of the tool supporting shafts is cantilevered outwardly from oneface of the hold- 3,43 9,5 18 Patented Apr. 22, 1969 er base. Eachcantilevered shaft end provides means for journaling a thread formingtool or the like thereupon. Synchronizing drive means are supportedwithin the holder base and means are provided to establish a drivingconnection between each of the tools and the synchronizing drive meansfor synchronizing the rotation of the tools upon their respectivesupporting shaft ends.

Brief description of the drawings FIGURE 1 is a side elevational view ofa toolholder embodying this invention.

FIGURE 2 is a side elevational view of the toolholder on the sideopposite to that shown in FIGURE 1.

FIGURE 3 is an end elevational view of the toolholder, with a portionbroken away.

FIGURE 4 is a perspective view of one piece of the toolholder base.

FIGURE 5 is a cross sectional view taken along the line 55 of FIGURE 1.

FIGURE 6 is a cross sectional view taken along the line 66 of FIGURE 5.

FIGURE 7 is a cross sectional view taken along the line 77 of FIGURE 5.

FIGURE 8 is a cross sectional view taken along the line 88 of FIGURE 5.

FIGURE 9 is a cross sectional view taken along the line 99 of FIGURE 5.

FIGURE 10 is a cross sectional view taken along the line 1010 of FIGURE1.

FIGURE 11 is an enlarged cross sectional view taken along the line 1111of FIGURE 5.

Detailed description of the preferred embodiment of the invention Atoolholder base assembly embodying this invention is identifiedgenerally by the reference numeral 21, which base assembly is adapted torotatably support a pair of thread rolling tools 22 and 23 adjacent oneof its faces 24 and outboard thereof. It is to be understood that othertypes of rolling or forming tools may be supported by the holder baseassembly 21, for example, serrating tools, knurling tools or othersimilar forming tools commonly used with screw machines.

The base assembly 21 is comprised of a fixed top plate 25 on the sideopposite the face 24. The plate 25 has a pair of outwardly extendingarms 26 and 27 that define a workpiece receiving recess 28. A dovetailportion 29 is formed integrally at the end of the plate 25 opposite thearms 26 and 27 for attachment of the holder base assembly 21 to acooperating screw machine or the like.

The fixed top plate 25 is fixed to an adjacent fixed sup porting block,indicated generally by the reference numeral 31 and shown in perspectivein FIGURE 4 of the drawings. The fixed block 31 is substantially thesame in shape as the outer periphery of the adjacent portion top plate25 and like the plate 29 is formed with a dovetail portion 32. Parallelbores 33 and 34 are formed in plate 25 and block 29. The bore 34 in theblock 31 is tapped so as to receive a socket headed bolt 35 that isreceived in a counter bored hole in the face plate 25 and threaded intothe tapped hole 34 to assist in holding the face plate 25 and fixedblock 31 together. The block 31 is also formed with another tapped hole36 into which a socket headed bolt 37 is threaded, which bolt alsopasses through an aligned counter bored opening on the face plate 25 tohold these parts together.

The portion of the block 31 adjacent the arm 26 is formed with a taperedbore 38 that receives a shaft 39 that extends at one end past the face24 to support the tool 22 in a manner which will become more apparent asthis description proceeds.

The block 31 is formed with a cutout 41 adjacent the dovetail portion 32and next to the plate 25. An extending ear 42 of a pivoted blockassembly, indicated generally by the reference numeral 43 extends intothe cutout 41. The block 43 is formed with a bore 44 through which asmooth portion 45 of a socket headed shaft 46 extends. The socket headedshaft 46 is screw threaded, as at 47, and is received in a tapped hole48 in the plate 25. The shaft 46, therefore, forms a journal about whichthe block assembly 43 may pivot.

The angular position of the pivoted block 43 with respect to the fixedblock 32 is maintained in part by a pair of elongated socket headedbolts 51 that extend through tapered bores 52 (FIGURE 6) formed in theblock 43. The bolts 51 are tapped into threaded holes 53 formed in theblock 31 above the recess 41. The head of each bolt 51 bears against arespective shoulder 54 formed in the block 43 by a counter bored slot 55so as to preclude pivotal movement of the block 43 with respect to theblock 32 in a clockwise direction about the shaft 46 as viewed in FIGURE6. Pivotal movement in the opposite direction is precluded by theengagement of a stud 56 (FIGURE 8) with a shoulder 57 formed on theblock 29. The stud 56 is threaded into a tapped bore 58 formed in theblock 43 (FIGURES 5 and 8) The block 43 is formed with a tapered bore 61adjacent the plate arm 27 to supportingly receive a shaft 62 thatextends outwardly from the toolholder face 24. This cantilevered shaftend supports the tool 23 in a manner which will become more apparent asthis description proceeds.

The shafts 39 and 62 are held axially within the holder assembly 21 bymeans of socket headed bolts 65 and 66 that are threaded into tappedholes 67 and 68 formed in the outer ends of the shafts 39 and 62,respectively.

The head of the bolt 65 is received in a counterbore formed in a plate25 and in addition to axially fixing the shaft 39 helps to restrain theblock 32 with respect to the plate 25. The head of the bolt 66 isreceived in elongated counterbored slot 71 formed in the plate 25 andbears against a shoulder formed at the base of the slot 71 to affix theblock 43 with respect to the plate 25 as well as axially restrain theshaft 62. The elongation of the slot 71 permits angular adjustment ofthe block 43 with respect to the plate 25, however, as will become moreapparent as this description proceeds.

A fixed bottom plate 72 is secured to the outer face of the fixed block32 by means of flat headed bolts 73 (FIG- URE 2). The plate 72 is formedwith a grooved portion 74 (FIGURE 5) that receives an outwardlyextending tongue 75 of a bottom plate 76 that is affixed to the pivotedblock 43 by means of fiat headed bolts 77.

The outer end of the shaft 39 is formed with an enlarged diameter headportion 81 that is received in a recess 82 formed in the outer face ofthe thread cutting tool 22. A needle or roller type thrust bearing 83 isinterposed be tween the head portion 81 and the shoulder formed at thebase of the counterbore 82. A needle or roller type thrust bearing 85 isalso interposed between the inner face of the thread cutting tool 22 andthe outer face 24 of the cover portion 72. Thus, the threaded cuttingtool 22 is axially held onto the shaft 39 between the thrust bearings 83and 85 by the tension exerted on the shaft by bolt 65. The rolling tool22 is, however, free to rotate upon a bushing 86 and upon thecantilevered shaft end. A like construction is provided for supportingthe thread rolling tool 23 on the outer end of the shaft 62 and likereference numerals have been used to identify the thrust bearings andbushing.

The thread rolling tools 22 and 23 are interconnected by means of asynchronizing gear train, indicated generally by the reference numeral87 and shown in most detail in FIGURE 7, so that their rotation will besynchronized when a workpiece is presented to them. The gear train 87consists of a first gear 88 that is journaled upon the shaft 39 within arecess 89 formed in the face of the block 31 adjacent the plate 72. Thegear 88 is formed with a pair of integral, forwardly extending keys 91(FIGURE 1) that are received in somewhat larger keyways 92 formed in theinner face of the thread rolling tool 22. The keys 91 and keyways 92thus form a driving connection between the gear 88 and the threadrolling tool 22 while allowing for some lost motion.

The gear 88 is in mesh with a larger diameter gear 93 that is journaledupon a stub shaft 94 that is threaded into the block 31. The gear 93 ispositioned within a recessed portion 95 of the block 31 adjacent theplate 72 and is held in axial alignment by the plate 72.

The shaft 46 is provided with a reduced diameter end portion 96 thatextends through a bore in block 31 and on which a gear 97 is journaled.The gear 97 is axially held onto the shaft portion 96 by means of a snapring 98 and is in mesh with the gear 93 and with a gear 99 that issupported upon a threaded stub shaft 101 that is received in a tappedhole 102 formed in the pivoted block 43 (FIG. 10). The gear 99 issupported within a recess 103 formed in the outer face of a block 43adjacent the plate 76 and axially fixed in place thereby. The gear 99 isengaged with a gear 105 that is journaled upon the shaft 62 and receivedwithin a cavity 106 formed in the block 43 adjacent the plate 76. Thegear 105 also carries outwardly extending keys 107 that are received inenlarged keyways formed in the rolling tool 23 so that a drivingconnection with some lost motion is provided therebetween. The geartrain 87 insures that the rolling tools 22 and 23 will rotate in unisonbut in opposite directions inasmuch as the rolling tools 22 and 23engage opposite sides of the piece being threaded. The lost motionconnections between the rolling tools and the gear train 87 insureproper synchronization when a rotating workpiece is fed into the cuttingtools 22 and 23.

Each of the gears 88, 93, 97, 99 and 105 of the gear train 87 is thussupported in a respective recess in one of the blocks 31 or 43. Each ofthese recesses, with the exception of a recess 108 in which the gear 97is contained, which recess is formed in the block 31, is ofsubstantially the same depth as the thickness of the respective gear.The cover plates 72 and 76 thus serve to axially confine the respectivegears within the respective cavities and axially fix the gears upontheir respective supporting shafts. The cavity 108 has a depth that isat least equal to twice the thickness of the gear 97 for a reason whichwill become more apparent as this description proceeds.

As has been noted, the bores 38 and 61 that support the shafts 39 and62, respectively, are tapered. Preferably these bores have a 1 taperwith the smaller diameter portion being adjacent the face 24. Each ofthe shafts 39 and 62 is provided with a longitudinally extending slot111 and 112, respectively. Headed studs 113 and 114 are tapped into theblock 31 and engage the shaft 39 within slot 111 to preclude rotation ofthe shaft 39. In addition, the axial orientation of the shaft 39 withrespect to the bore 38 can be altered by proper adjustment of the studs113 and 114. A stud 115 bears against the inner end of the shaft 39adjacent the larger diameter portion of the tapered bore 38 tofacilitate the adjustment and assist in locating the shaft 39. Similarheaded studs, identified by the same reference numerals, engage theshaft 62 so as to alter its axial location with respect to itssupporting bore 61. Adjustment of the studs 113, 114 and 115 permitscorrection of the alignment of the axes of rotation of the cutting tools22 and 23 to compensate for any wear that may occur in the parts. Theaxis of the studs 115 are displaced something less than from the axes ofthe studs 113 and 114 so as to facilitate this adjustment.

The disclosed toolholder assembly 21 is constructed in such a mannerthat it is extremely compact but is nevertheless extremely rigid so asto withstand the forming loads. The outboard mounting of the rollingtools 22 and 23 is accomplished without necessitating expensive thrustbearings inasmuch as the supporting shafts 39 and 62 are fixed againstrotation within the holder base assembly 21. Thrust bearings need not beemployed, therefore, to restrain the axial movement of these shafts.

If it is desired to change the tools supported upon the shafts 39 and62, the socket headed bolts 65 and 66 are removed and the studs 113, 114and 115 may be backed off slightly. The shafts 39 and 62 can then beslid axially out of the holder base assembly 21 along with the rollingtools 22 and 23. When new rolling tools are inserted upon the shafts 39and 62 these shafts may again be inserted into the holder base assembly21 and locked in position by insertion of the bolts 65 and 66 andappropriate adjustment of the studs 113, 114 and 115.

In some instances it may be desirable to alter the spacing between theshafts 39 and 62 and their respective rolling tools. This adjustment mayreadily be effected by loosening the socket headed bolt 66 and anothersocket headed bolt 121 that extends through an elongated counterboredslot 122 formed in the plate 25, which bolt is tapped into a threadedhole 123 formed in the block 43 (FIG. 6). The bolts 51 and stud 56 maythen be adjusted in an appropriate manner so as to cause the block 43 topivot about the shaft portion 46 with respect to the block 31. Thisadjustment is facilitated since the head of the stud 56 is accessiblethrough an opening 124 formed in the side of the block 43 (FIG. 3). Theelongation of the slots 71 and 122 in the plate 25 permit thisadjustment, and when the desired adjustment is reached, the bolts 66 and122 are retightened.

Upon changing the distance between the shafts 39 and 62 or under someother circumstances it may be necessary or desirable to adjust theangular relationship between the gears 88 and 105 to insure propersynchronization of the rolling tools. This adjustment may also beefiected externally by inserting a proper tool into the socket head ofthe shaft 46 and turning this shaft. Rotation of the shaft 46 will causeaxial movement of this shaft and axial movement of the gear 97 withinthe cavity 106 due to the threaded connection 47, 48. The cavity 108 hassufficient depth to permit the gear 97 to be moved completely out ofmesh with the gears 93 and 99. Thus, the gear 88 may be rotatedindependently of the gear 105 or vice-versa. When the desired angularrelationship is reached, 'the shaft 46 is rotated in the oppositedirection to bring the gear 97 back into mesh with the gears 93 and 99and the desired synchronization will have been effected.

While it will be apparent that the preferred embodiments of theinvention disclosed are well calculated to fulfill the objects abovestated, it will be appreciated that the invention is susceptible tomodification, variation and change without departing from the properscope or fair meaning of the subjoined claims.

What is claimed is:

1. A toolholder for thread rolling tools or the like comprising a holderbase, a pair of spaced tool supporting shafts held against rotation bysaid holder base, one end of each of said tool supporting shafts beingcantilevered outwardly from one face of said holder base, eachcantilevered shaft end providing means for journaling a thread formingtool or the like thereupon, synchronizing drive means supported withinsaid holder base, and means for establishing a driving connectionbetween each of the tools and said synchronizing drive means forsynchronizing the rotation of the tools upon their respective supportingshaft ends.

2. A toolholder as set forth in claim 1 wherein each of the cantileveredshaft ends has an enlarged diameter end portion adapted to provide areaction surface against which a thrust bearing may react between saidsurface and the supported tool, the adjacent face of said holder baseproviding a reaction surface against which another thrust bearing mayreact.

3. A toolholder as set forth in claim 1 further including means forangularly adjusting at least one of the supporting shafts to compensatefor wear.

4. A toolholder as set forth in claim 1 wherein the tool supportingshafts are supported by the holder base for adjustment of the distancebetween said shafts.

5. A toolholder as set forth in claim 4 wherein the holder basecomprises a first block and a second block pivotally supported withrespect to said first block, said first block supporting one of the toolsupporting shafts and said second block supporting the other toolsupporting shaft whereby the adjustment of the distance between saidshafts is effected by pivotal movement of said blocks with respect toeach other.

6. A toolholder as set forth in claim 5 wherein each of said blocks isprovided with recesses in the side adjacent the cantilevered ends of thetool supporting shafts, the synchronizing drive means comprising a geartrain supported within said holder base with the respective gears beingpositioned in the respective cavities of said blocks.

7. A toolholder as set forth in claim 6 further including means formoving one of the gears out of engagement with other of the gears toadjust the synchronization between the tools.

8. A- toolholder as set forth in claim 7 wherein the means for movingthe one gear out of engagement with other of the gears comprises a shaftsupported by one of the blocks and axially movable with respect thereto,said one gear being r-otatably suported on said shaft and held againstaxial movement with respect thereto for movement of said one gear out ofengagement with said other gears upon axial movement of said shaft.

9. A toolholder as set forth in claim 8 wherein the shaft supporting theone gear pivotally supports the second block with respect to the firstblock.

10. A toolholder as set forth in claim 9 wherein each of the blocks isformed with a tapered bore in which the respective tool supporting shaftis positioned, and means for holding each of said tool supporting shaftsagainst rotation within said bore and for adjusting the angular positionof each tool supporting shaft with respect to said bore.

References Cited UNITED STATES PATENTS 541,551 6/1895 Johnson 72-1032,550,855 5/1951 Ostendorf 72--104 2,974,550 3/1961 Eigenbrode 72-101CHARLES W. LANHAM, Primary Examiner.

L. A. LARSON, Assistant Examiner.

US. Cl. X.R. 72104

